Dendroctonus valens LeConte(Scolytidae), was first detected in Shanxi Province, northern China, in 1998 and started causing widespread tree mortality in 1999. This outbreak continues and has spread to three adjacent provinces, causing unprecedented tree mortality. In North America, it is considered to be a secondary pest, and is often associated with more aggressive bark beetle species. The bionomics and occurrence, response to host volatiles and host preferences of this pine beetle in China are different from what is known of the beetle in its native range in North America. Changes in D. valens invasion characteristics after introduction into China, were evaluated from damage to Pinus tabulaeformi forests at the Lingkonshan Forest Farm in Shanxi Province, and the Xiaolongmen Forest Farm in Beijing, from July to August in 2009. Health stages of P. tabulaeformis were considered to be one cell of the spatial resources of D. valens population based on niche theory, and they were divided into healthy wood, mild weak wood, moderate weak wood, dying wood, and withering wood. In addition, historical data on D. valens was examined to establish its invasion characteristics in China. Based on niche theory, the niche breadth of D. valens was narrow, it barely affected moderate weak wood, dying wood and withering wood, while it primarily invaded both healthy and mild weak wood, and was a primary pest. Through searching historical data on D. valens at the Huanglongshan Forest Farm in Shanxi Province, Lingkonshan Forest Farm in Shanxi Province, Xingjiayu Forest Farm in Hebei Province, and the Xiaolongmen Forest Farm in Beijing, D. valens originally invaded weak and injured wood, but now it mainly invades both healthy and mild weak wood, and is a primary pest. This helps to explain the population expansion and colonization mechanism of D. valens, and to provide a good reference point for adopting suitable control measures.